Ignitions Systems Descriptions; Operating Principles - Honda Motorcycle Service Manual

IGNITION SYSTEMS
SYSTEM DESCRIPTIONS
Most motorcycles use electrically controlled ignition systems. These ignition systems can be divided into CDI or transister-
ized types, depending on how they operate. Although their function is the same, the way they operate is different. In order
to s e ~ i c e these systems, one needs t o understand their basic operation. Since both control their ignition-system compo-
nents electrically, there is no mechanical wear, and periodic maintenance and adjustment are unnecessary.
CDI
The term CDI is on abbreviation for "Capacitive Discharge Ignition." The CDI produces quick and stable secondary voltage
and is resistant to spark plug fouling. It is also designed t o increase its secondary voltage as rpm increases.
Operating Principles
AS the alternator rotor turns, current is induced i n the alter-
nator (exciter coil) This current (AC) is fed to the ignition
control module with a voltage o f 100-400 volts. This AC
current is half-wave rectified bv a diode and is stored i n the
capacitor inside the ignition control module.
When the engine is turned off, the current induced by the ex-
citer coil is shorted to ground, thus cutting off current to the
capacitor and turning off the spark.
The capacitor cannot discharge until the SCR is turned ON.
The SCR is turned ON as the ignition pulse generator sends
pulses to the trigger circuit which, in turn, feeds current to the
gate of SCR.
/ - -
lGNlTlON1ENGlNE STOP SWITCH
CAPACITOR (Discharge)
,
GENELATOR
When the SCR is turned ON, the capacitor discharges current
1
SPARK PLUG WIRE
t o the ignition primary coil A high voltage surge induced i n
secondary coil jumps the spark plug gap.
NOTE
.
This circuitry is also controlled by one additional circuit
on models equipped with a side stand ignition cut-off
system.
/
SPARK PLUG
23-4
Date of Issue: March, 1995
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HONDA MOTOR CO.,LTD.